Wednesday 27 March 2013 07.54 EDT
First published on Wednesday 27 March 2013 07.54 EDT

The home secretary, Theresa May, has lost her latest legal attempt to deport the radical Islamist cleric Abu Qatada back to Jordan.

The three appeal court judges, who unanimously dismissed May's appeal, reminded her in their ruling that "torture is universally abhorred as an evil", and states cannot expel someone where there is a real risk that they will face a trial based on evidence obtained by torture.

The appeal court ruling by the master of the rolls, Lord Dyson, with Lord Justice Richards and Lord Justice Elias, threw out the home secretary's attempt to overturn a ruling last November by the special immigrations appeals commission (Siac) in London blocking Qatada's return to Jordan to stand trial because "there was a real risk he would be subject to a flagrant denial of justice".

The appeal court judges said they recognised, however, that Qatada was "regarded as a very dangerous person" and that the British government considered him to be a danger to national security, adding: "It is entirely understandable that there is a general feeling that his deportation to Jordan to face trial is long overdue."

But they said the fact he was considered a "dangerous terrorist" was irrelevant to their decision on whether Siac had made an error in law when it decided he would face a "flagrant denial of justice" if he was sent back to Jordan.

"Torture is universally abhorred as an evil," they said in their ruling. "A state cannot expel a person to another state where there is a real risk he will be tried on the basis of evidence which there is a real possibility may have been obtained by torture. That principle is accepted by the secretary of state and is not in doubt."

They said Siac had applied that principle in the light of all the evidence in Qatada's case, and had committed no error of law in the process.

The ruling will fuel the already heated clash between the home secretary and the judges over the future of human rights legislation in Britain. May has already accused the courts of "moving the goalposts" in the Qatada case and repeatedly personally backed the repeal of the Human Rights Act.

May's legal options are now running out fast in the Qatada case, and she faces a decision over whether or not to return to Jordan to seek even stronger assurances that he will face a fair trial on his return. It seems May's "twin track" strategy of battling for Qatada's removal in the courts and through diplomatic pressure on Jordan is now under severe pressure.

A Home Office spokesman said: "This is not the end of the road. The government remains determined to deport Abu Qatada. We will consider this judgment carefully, and plan to seek leave to appeal. Meanwhile, work will continue with Jordan to address the outstanding legal issues preventing deportation."

But it is hard to see how a further appeal by the home secretary to the supreme court could succeed, as it has to be based on a fresh point of law.

The shadow home secretary, Yvette Cooper, said the ruling was "an extremely serious and disappointing judgment which rips apart Theresa May's strategy for deporting Abu Qatada and contradicts her repeated assurances to parliament that her approach would get him swiftly on to a plane. The home secretary needs to pursue all legal avenues, demonstrate further work with Jordan, take urgent action to keep the public safe, and get this deportation back on track."

The ruling follows a one-day appeal court hearing earlier this month during which James Eadie QC, on behalf of the home secretary, argued that Siac – in effect Britain's anti-terror court – had "erred in law" and taken the wrong approach when it concluded that Qatada could not be sent back to Jordan because he would not face a fair trial.

Siac blocked Qatada's deportation in November on the grounds that there was a "real risk" that the retrial he would face in the state security court for bombing offences dating back to 1998 – for which he has been convicted in his absence – would be based on evidence obtained by torture from his co-defendants Abu Hawsher and Al-Hamasher.

The Siac judge Mr Justice Mitting said the diplomatic assurances obtained by May were insufficient to prove that torture-based evidence would not be admitted in any retrial.

He said the risk would remain until Jordan amended its code of criminal practice or there was a ruling by the Amman constitutional court that such evidence could not be used in a trial. The only other alternative was for the Jordanian prosecutor to prove "to a high standard that the statements were not obtained by torture".

Mitting upheld the ruling by the European court of human rights last year that Qatada would face a "flagrant denial of justice" if he were sent back to Jordan to face trial. His lawyer, Edward Fitzgerald QC, has maintained there is "concrete and compelling evidence" that Qatada's co-defendants were tortured.

Qatada was first detained in Britain as an international terror suspect more than 10 years ago under the Belmarsh regime of emergency terrorism legislation, which was ruled illegal. Successive home secretaries have been attempting to deport him since 2005.

It is now 11 months since the current home secretary told the Commons: "We can soon put Abu Qatada on a plane and out of the country for good." The radical cleric, who was released on bail with a 16-hour-a-day curfew to a London address after last November's Siac ruling, was rearrested and taken back into custody two weeks ago.

The Metropolitan police said they had seized a vast amount of extremist material, including online and print publications, in searches of his north London home.